Conventionally, a pipe-like lead guide is attached and fixed to a base in a mechanical pencil. According to this structure, if an amount of projection of the writing lead projecting from a lead guide is large, breakage of the lead (lead breakage) may occur when writing. Thus, it is necessary to limit a projection length of the lead which projects from a lead guide by one knock operation.
For this reason, according to consumption of the lead due to the writing operation, we are obliged to frequently carry out knock operation for a knock bar provided at a rear end portion of a lead storage. In other words, there is a problem in that having to change a grip and to perform the knock operation when writing reduces writing efficiency.
Then, for example, patent documents 1 and 2 etc. below propose and disclose a pipe-slide type mechanical pencil which operates such that, as the writing lead projects due to the knock operation, a pipe-like lead guide also moves forward; as the lead is abraded while the writing proceeds, the lead guide may also retreat.    Patent Document 1: Japanese Patent Application Publication No. H8-072473    Patent Document 2: Japanese Patent Application Publication No. H8-132782